Hallo nobilityhouse, thank you very much. I found the arms of Riqueti de Mirabeau in
(admin edit - see Posting Requirements )
It is the heraldic right part of my (I suppose) Allianzwappen. In the net I only got information about Mirabeau, politician during the French revolution, nothing about descendants. There must have been somebody in the first half of the 20th century, because my flatware is marked in that time. Remains the question of the second coat of arms.
Regards silverfan